Note: Descriptions are shown in the official language in which they were submitted.
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REVISED SPLINE DRIVE
FOR METAL BRLT CVT
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Description
The present invention relates to a continuously
variable transmission, at times referred to as a CVT.
Transmissions of this type are well known in the art,
and comprise a pair of cone pulleys, each comprising a
pair of sheaves or flanges, the pulleys beiny drivingly
interconnected by a belt or the like. In the usual CVT,
one pulley is connected to a drive shaft. At least one
flange of each pulley is axially movable, with respect
to the other flange, on its respective shaft. By
varying the spacing between each pair of flanges of each
pulleyl continuous adjustment of the drive ratio can be
provided between the shafts within the limits of pulley
sizes. Means are usually provided for initiating the
drive ratio changes and the prior art is replete with
techniques of such means.
The axially movable flange of each pulley or a hub
of such flange may be, according to the prior art, each
provided with an internal keyway to receive a key
received in a keyway in the respective shaft, thus
providing the driving connection between flange and
shaft while permitting the axial movement of the flange.
Lubricating the key-keyway connection is difficult at
times. Thus the key binds in the keyways and the
movable flange behaves as a fixed flange, so that drive
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ratio changes are impeded. Loading on the key, under these
circumstances, becomes excessive because of the physical mass
of the pulley rotating at relatively high speeds, leading
to premature failure of the transmission.
Another form of movable flange-shaft connection
is the ball-spline in which a plurality of balls are used
with a spline, the balls functioning as anti-friction elements.
The ball-spline connection is loca-ted internally of the flange
and/or its hub. Ball-spline connections are expensive and
also require continual lubrication to insure continued perfor-
mance. Loading on the spline of the ball-spline connection
can also become excessive, leading to premature failure of
the connection.
The variable pulley transmission, according to
this invention, comprises the usual pair of interconnected
cone pulleys, each having a pair of flanges, with at least
one flange of each pair being axially movable with respect
to the other flange of the pair, along its respective shaft.
However, the driving connection between the axially movable
flange of a pulley and its shaft is modified in such a manner
that belt loads are not absorbed by a splined drive connection
but are totally transmitted to the sha-Et-pulley or sheave
interface.
According to the present invention there is provided
a pair of pulley flanges defining a V space therebetween,
one flange being fixedly positioned and the other being axially
movable with respect to the fixedly positioned flange. Means
is provided for imparting rotation to the pulley, the means
including a rotating means and means connecting the fixedly
positioned flange to the rotating means. Means is provided
for connecting the axlally movable flange to the rotation
means while permitting the axial movement thereof. The means
includes an externallysplined member connected to the axially
movable flange and a meshing internal spline coupling member
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connected to the rotation means.
More specifically, the axially movable flange
of each pulley is formed with an axially extending shoulder
internally finished to surround, and be axially movable with
respect to, its shaft. A cylindrical, externally splined
ring is press-fi.t over the shoulder of the
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~lange. An axially extending flange of a cup-shaped
torque transfer member is press-fit onto the shaft, and
is provided with an internal spline which mates with the
external spline of the pulley flange. The external
spline is capable of axial movement with respect to the
internal spline. A second cup-shaped housing member
surrounds and is connected to the torque transfer member
such that an axially extending cylindrical portion of
the pulley flange forms a cylindrical cavity. Passage
means provide a path for lubricant to flow into the
cavity which has, within its boundaries, the internal-
external spline arrangement described, thus insuring
continued lubrication of the spline connection.
One way of carr~ing out the invention is described
in detail below with reference to drawings which illus-
trate only one specific embodiment, in which:-
Figs. 1 and 2 are perspective illustrations of avariable pulley transmission arrangement in two drive
ratios;
Fig. 3 is a cross-sectional view through one of the
pulleys of a pulley transmission constructed according
to this invention, illustrating one extreme position of
a pulley flange in solid lines and the other in broken
lines; and
Fig. 4 is a cross-sectional view, taken on line 44
of Fig~ 3O
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Figs. 1 and 2 illustrate, schematically, a con-
tinuously variable pulley transmission (CVT) which
comprises first and second shafts 10 and 12, each
having drivingly connected thereto a cone pulley, 14 and
16, respectively, intercoupled by a belt means 18~ One
of the shafts is a drive shaft connected to a power
source, such as the en~ine of a motor vehicle (not
shown), and the other shaft is a driven shaft connected
to the output mechanism (not shown) of the driven
device. The pulley 14 comprises a pair of sheaves or
flanges 20, 22, at least one of which is axially movable
with respect to the other along shaft 10. The pulley 16
comprises a pair of sheaves or flanges 2~ r 26, at least
one of which is axially movable with respect to the
other along shaft 12. As observed, the two drive
ratios depicted are the extreme ratios, it being under-
stood that drive ratios between the extremes are pro-
vided depending upon the position of the belt with
respect to the pulleys, or, in other words, depending
upon the spacing of the pulley flanges in the trans-
mission. While the pulleys are illustrated in Figs. 1
and 2 as having different diametersl they could be of
the same diameter without departing from the spirit of
the invention.
Figs. 3 and 4 are particularly useful in describing
the present invention. Only one of the two cone pulleys
is illustrated, as the driving construction of the
omitted pulley is substantially the same as that illus-
trated.
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In Figs. 3 and 4, the pulley 3U (shown in solid
lines in one extreme drive ratio and in broken lines in
the other extreme drive ratio in Fig. 3) i5 drivingly
connected to the shaft 32. Pulley 30 comprises a
first flange 34, illustrated as integrally formed with
the shaft 32 and a second flange 36 axial.ly movable with
respect to the flange 34 along shaft 32. The flange
36 is formed with a rearwardly extending, generally
cylindrical hub 38 which has an internal diameter sized
to be axially slidable on the shaft 32, and an external
cylindrical surface on~o which a ring member 40 is
pressfit. The ring member 40 is externally splined, as
best illustrated in Fig. 4, to thus present a plurality
of external splines 42. The ring member 40 can, if
desired, be made integral with hub 38 of flange 36.
A cup-shaped drive member 44 is internally splined
to present a plurality of internal. splines 46 which mesh
with splines 42. The member 44 has an axially extending
cylindrical portion 48 press-fit or otherwise secured
onto the shaft 32, thus providing a driving connection
between the flange 36 and the shaft 32 with the splined
connect.ion permitting axial movement of the flange 36
relative to the shaft. A retaining nut 50 received on a
threaded part of the shaft 32 insures the axial posi-
tioning of the drive member 44 on the shaft.
A cup-shaped closure member 52 surrounds the drive
member 44, and abuts a flange 54 of that drive member.
Member 52 is sealed thereto by an O-ring 56 and pos-
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itioned by a snap ring 58. The member 52 has a forward-
ly extending flange 60, which surrounds a rearwardly
extending flange 62 of the pulley flange 36. An O-ring
64 seals the flange 60 to the flange 62, yet permits
axial movement therebetween~ The st:ructure described
defines a chamber 66 into which oil is permitted to flow
through a passage-way 68 in the hub 38, and passageways
70 in the shaft 32, from a sump (not shown)~ Oil is
also discharged from chamber 66 through the described
passageways, when the efective pulley diameter is
increasedO Some of the oil from the chamber 66 insures
adequate lubrication of the spline connection, lubri-
cation of the shaft-hub juncture and lubrication of the
flange 60-flange 62 juncture.
The appended claims are intended to cover all
reasonable equivalents of the structure described.
